MOSCOW, January 17 - RAPSI. Law enforcement officers are looking for a sharpshooter who killed criminal boss Aslan Usoyan in central Moscow on Wednesday, RIA Novosti reports.

Usoyan, known as Grandpa Hassan, was killed in broad daylight in central Moscow. According to investigators, the killer, who has escaped, shot the criminal boss from a window of the building across from Usoyan's favorite restaurant.

When the sniper wounded Usoyan in the neck, his bodyguards carried him back into the restaurant, closed the door and shot back at the killer without hitting him. The gunman made several more shots at the closed door of the restaurant, gravely wounding a female employee in the leg and the chest.

Usoyan was still alive when his bodyguards rushed him to a hospital, but the doctors could not save him. They operated on the wounded restaurant employee, who is in critical condition.

Investigators say the gunman used a Val assault rifle with an integrated suppressor as issued to the Russian Special Forces. The rifle cannot be purchased legally and is extremely difficult to obtain on the black market. Investigators believe the sniper could be a retired Special Forces officer or a professional biathlete.

It was not the first attempt on Usoyan's life. In 2010, a sniper shot at him and his bodyguard in central Moscow as the criminal boss was entering a building. That gunman used a silenced Kalashnikov rifle. Usoyan was wounded in the belly; the gunman was never found.

Grandpa Hassan was one of the most respected criminal bosses in Russia. According to the Russian media, he was recently active in helping settle disputes between mobs, but was also allegedly at war with the criminal group led by Tariel Oniani, who is serving a 10-year sentence for kidnapping.